In general, a nitride semiconductor material including a source, such as nitrogen (N) of group V and a source, such as gallium (Ga), aluminum (Al), or indium (In), of group III has excellent thermal stability and a direct transition energy band structure. Accordingly, the nitride semiconductor material has been extensively used as a material for a nitride semiconductor device, that is, a UV nitride semiconductor, and a solar cell material.
The nitride-based material has a wide energy bandgap in a range of 0.7 eV to 6.2 eV, which is matched with the spectrum of the solar cell. Accordingly, the nitride material has been mainly used as a material for the solar cell. In particular, the UV light emitting device has been utilized in various industrial fields, such as a hardening device, a medical analyzer, curing equipment, and a sterilization and purification system. The UV light emitting device has been spotlighted as a material available to typical lighting as a semiconductor lighting light source in the future.